This invention relates to a method and an apparatus for feeding a fiber tuft opener or cleaner associated with a fiber tuft feeder which forms a fiber lap or mat to be introduced into the opener or cleaner. Since the invention may find application in connection with a textile machine such as a cleaner or an opener, which, as the input material, uses a fiber lap, hereafter any reference to a cleaner should be understood to apply to an opener or similar apparatus as well.
The efficiency of a fiber tuft cleaner depends to a great measure on the quality of the fiber lap introduced thereinto. Therefore, a uniformity of the fiber lap both in the width and longitudinal directions is of importance. In a known apparatus, the fiber lap is produced by deflecting the fiber columns formed in the feed chute of the tuft feeder. The feed chute may be of the pneumatic type in which the fiber column is compressed by an air stream. The thickness of the fiber column depends from the pressure of the compressing air stream and from the mutual distance of the chute walls. In other types of feed chutes, the column is formed in the feed chute by a free fall of the fiber tufts. In such a case the lap thickness depends from the fill height of the tufts and from the mutual distance of the feed chutes walls.
In case of a feed chute of the free fall type, the minimum obtainable lap thickness is limited: the chute requires a minimum distance between the chute walls to ensure that the fiber material is capable of sliding downwardly without forming bridges between the walls which would lead to a lack of homogeneity of the fiber column. In the case of pneumatic feed chutes in which the distance between the chute walls may be substantially smaller than in the chutes of the free fall type, a limitation exists since the feed chute requires a certain air throughput to ensure the downward slide of the fiber material and its corresponding densification. By virtue of the tuft compression, however, between the narrow feed chute walls a significantly heavier material layer is present than in the chutes of the free fall type. Thus, in the known methods, it is not feasible to produce the desired, thin, uniform fiber lap for the cleaner. It has been found that photocells provided in the chutes of the free fall type for monitoring the filling height have required such fill height fluctuations for the operation of the machine that even the smallest fill heights have produced an excessively dense fiber lap.